You can use any svg editor you like, but many of us here (including me) use Inkscape so you are more likely to get support for it. That said you have a number of problems in these files starting with no layerIds and no connectors. You would be much better off to unzip this part (which will produce an fzp file and 4 svg files) and modify it because it appears to be the correct format with a quick glance:
NRF24L01 _Breakout_Board.fzpz (22.1 KB)
About the only tutorials that really apply to the current version of fritzing are these (one by me more by Old_Grey):
A new part creation HowTo (long! So long it is in 2 posts)
There is also a part checking script available here:
and the part file format document available here (which is what the script above uses to check parts along with a bunch of common errors I have run across).
There are also graphics standards documents in the learning section of the main web site that are worth reading and obeying.
One of Inkscape’s many quirks is that it will not select (and therefore drag) a drawing element that has a 0 height or width (which many terminals in existing parts have). I generally change that first thing when changing a new part.
Peter